New polyacetal, poly(ester‐acetal) and their urethane‐modified coatings from hydroformylated linseed oil

Partly hydroformylated linseed oil, with an average of 1.3 to 3.4 meq aldehyde per gram of oil, was reacted with pentaerythritol hydroxymethyl linseed oil and trimethylolpropane in the presence of an acid catalyst to form viscous, high molecular weight polyacetals. Isophthalic acid or chlorendic anhydride‐modified polyacetals [poly(ester‐acetals)] were prepared by reacting the trimethylolpropane esters of the acids with the hydroformylated oils. Films of the products were cured at room temperature and at 140 C. These films showed good hardness as well as chemical and impact resistance. Further modification of these polyacetals and poly(ester‐acetals) by reacting the residual hydroxyl groups with an excess of toluene diisocyanate gave the corresponding isocyanate‐terminated prepolymers. Films from these prepolymers had shorter drying times and showed greater hardness than the corresponding unmodified materials.